m7G Trac-Seq analysis in LNZ308 METTL1 knockdown cells

The RNA methyltransferase METTL1 catalyzes the N7-methylguanosine (m7G) modification of certain tRNAs, mRNAs, and miRNA precursors. However, the role of METTL1 and its cofactor WDR4 in cancer remains largely unexplored. Here we reveal the oncogenic role of METTL1/WDR4. METTL1 is frequently amplified and overexpressed in cancers and correlates with poor patient survival. METTL1 depletion in human cancer cells causes decreased abundance of m7G-modified tRNAs, altered cell cycle, and inhibits oncogenicity. Strikingly, METTL1/WDR4 overexpression induces oncogenic transformation and carcinogenesis. Mechanistically, we find increased abundance of a subset of m7G-modified tRNAs including tRNA-Arg(TCT), and increased translation of mRNAs enriched in the corresponding AGA codon including cell cycle regulators. Accordingly, expression of tRNA-Arg(TCT) is significantly elevated in many cancer types, correlates with patient survival, and overexpression of this tRNA enhances reporter gene expression and cell transformation. Thus, METTL1/WDR4-mediated m7G tRNA modification drives oncogenic transformation, thereby highlighting METTL1 as a promising cancer therapeutic target. Overall design: Examination of m7G modification in METTL1 silenced LNZ308 human glioblastoma cells compared to shGFP control cells, in duplicate, using Trac-Seq techique. Input samples were used for abundance determination and cleaved samples for m7G modification analysis.